1) Summer colds are NOT caused by air conditioning. In fact, I wish they were. That would mean I have air conditioning.
2) When a man runs up and down your street shrieking and dancing with his pants down, call the Guardia Urbana. They're much quicker than the Mossos D'Esquadra.
3) When someone in Spain says "Um, no sorry, I can't do that," it generally means "Um, no sorry, I don't feel like doing that."
4) When you give your 77 year old next door neighbor a plate of cookies you've made, be prepared to spend a couple hours in her apartment pouring over photos of her distant relatives and the tie-dyed scarves she's made at the old folks home while nodding along like you understand her bizarre strain of catalan/castellano/old lady.